This chapter has been dominated by technical matters. The British and United States rival themes of air attack by night or day have been shown under the hard test of results. The improvements in our explosives and the intricacies of Radar and all its variants have been presented, I trust, in a form intelligible to the lay reader. But it would be wrong to end without paying our tribute of respect and admiration to the officers and men who fought and died in this fearful battle of the air, the like of which had never before been known, or even with any precision imagined. The moral test to which the crew of a bomber were subjected reached the extreme limits of human valor and sacrifice. Here chance was carried to its most extreme and violent degree above all else. There was a rule that no one should go on more than thirty raids without a break. But many who entered on their last dozen wild adventures felt that the odds against them were increasing. How can one be lucky thirty times running in a world of averages and machinery? Detective-Constable McSweeney, one of the Scotland Yard officers who looked after me in the early days of the war, was determined to fight in a bomber. I saw him several times during his training and his fighting. One day, gay and jaunty as ever, but with a thoughtful look, he said, "My next will be my twenty-ninth." It was his last. Not only our hearts and admiration but our minds in strong comprehension of these ordeals must go out to these heroic men, whose duty to their country and their cause sustained them in superhuman trials. I have mentioned facts like "the Americans had sixty of their large Fortress aircraft destroyed out of 291", and on another occasion "out of 795 aircraft by British Bomber Command against Nuremberg ninety-four did not return". The American Fortresses carried a crew of ten men, and the British night bombers seven. Here we have each time six or seven hundred of these skilled, highly trained warriors lost in an hour. This was indeed ordeal by fire. In the British and American bombing of Germany and Italy during the war the casualties were over a hundred and forty thousand, and in the period with which this chapter deals there were more British and American air-crew casualties than there were killed and wounded in the great operation of crossing the Channel. They never flinched or failed. It is to their devotion that in no small measure we own our victory. Let us give them our salute.